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Location:
Ipswich
Registered:
October 2003
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Rear discs vs. better fronts
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Fri, 01 October 2004 04:14
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After calling an engineer regarding a 1g-gte --> ra28 conversion, I was told brake wise, he would want to see rear dics.
I asked if I could do a front brake upgrade instead, but he said no, to pass it, he would want to see rear discs, instead of a front brake upgrade.
My question is why? Don't the front brakes do 90% of the braking?
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Location:
c'town, NSW
Registered:
May 2002
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Re: Rear discs vs. better fronts
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Fri, 01 October 2004 04:16
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im not sure i follow 100%, to clarify here...
so the engineer said he'd be happy with stock front brakes as long as u put rear disks on?
....find another engineer....
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Registered:
May 2002
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Re: Rear discs vs. better fronts
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Fri, 01 October 2004 04:18
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I agree with the above, it does sound like a strange request (if the fronts are being left standard).
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Location:
Ipswich
Registered:
October 2003
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: Rear discs vs. better fronts
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Fri, 01 October 2004 04:43
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that is odd, but i'd want rear discs as well 
i hate drums, and to have a rear drum lock up kinda negates having any front brakes (when the car starts spinning)
find an engineer who wants both front and back upgraded 
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Location:
Melbourne
Registered:
October 2003
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Re: Rear discs vs. better fronts
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Fri, 01 October 2004 07:47
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maybe kill 2 birds with one stone since the stock diff is
going to go anyway, maybe shorten a VN diff? (cheap, stong, and comes stock with discs).
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Location:
Montrose, VIC
Registered:
May 2002
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Re: Rear discs vs. better fronts
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Fri, 01 October 2004 08:51
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There are still some people out there that believe the old idea that '4 wheel discs' = good brakes. Oh dear..
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Club Member
Location:
sydney
Registered:
May 2002
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Re: Rear discs vs. better fronts
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Fri, 01 October 2004 22:50
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Well .... any 4 disc combination will in most cases out peform a standard front disc and rear drum setup... but thats assuming you spend the time and money to set up the brake biasing correctly as well, its not a cheap and easy way to increase your braking power unless its a simple factory upgrade option somewhere along the line.
However.. If I were planning the conversion you are I would probhably opt for rear discs as well as upgrading the front, I suspect the engineer is trying to make sure you have plenty of stopping power so that you wont get yourself into a difficult situation... remeber that he doesent know what your driving abilities are so hes probhably trying to make sure both you are going to be safe and hes going to be covered from a lawsuit point of view.
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Location:
Brisbane
Registered:
May 2002
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Re: Rear discs vs. better fronts
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Sat, 02 October 2004 12:09
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It's obvious why he wants a brake upgrade (I think we'd all agree it's wise), but the weird thing is he won't allow a front brake upgrade while leaving the rears stock, which would clearly be far more beneficial than just upgrading the rears!
I agree though, upgrading both is the best way to go... if you can afford it.
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Location:
Brisbane
Registered:
February 2003
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Re: Rear discs vs. better fronts
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Sat, 02 October 2004 12:55
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matt,
<Kirk> from these forums dropped an 1G-GTE into his Ra28:
<http://www.eviltrip.com/77/>
i've not seen many posts from him on the forum lately, but he might respond to an email.
i9 think he did his conversion legit so he might know of a suitable engineer.
cheers,
Charles.
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Location:
Ipswich
Registered:
October 2003
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Re: Rear discs vs. better fronts
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Sat, 02 October 2004 15:03
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IRA11Y, what I was confused about was why rear discs would be preferable to a front brake upgrade. I know its not ideal to have a one or the other situation, but currently, it is. I thought due to the nature of braking systems, an equivalent amount of dosh in front/rear brakes would show a marked benefit in investing in the fronts?
Norbie, yeah, thats what I thought. I know i'd much rather put money into front brakes over rears. Although with a bit or searching, the volvo diff option so often proclaimed by a single pundit on these forums may be worth investigating. Both front and back may then be (financially) feasible.
Charles, i'll give him a go. Its either that or try explaining to an engineer why I think he's wrong. Ha. I think i'm gonna have to find another engineer.
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Location:
sunny coast, qld
Registered:
October 2002
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Re: Rear discs vs. better fronts
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Sat, 02 October 2004 22:45
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When I did my conversion I was told that I needed to have the same size brakes as the donor car from which the engine came. So in my case, I needed to have the same size brakes as a jzx90 chaser. Of course the engineer didn't know what size they were so jza70 supra then. This was only for the front brakes as far as I am aware. However, I already had a rear disk conversion with a Pajero diff and brakes which are large solid rotors and big single pistons.
I would be asking another engineer.
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Location:
tallahassee FL usOFa
Registered:
May 2002
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Re: Rear discs vs. better fronts
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Sun, 03 October 2004 00:25
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engineer?????
did he win a contest/drawing, or get a certificate from a cereal box?
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Location:
Brisbane
Registered:
May 2002
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Re: Rear discs vs. better fronts
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Sun, 03 October 2004 01:55
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The engineer I spoke to about my 2JZ conversion told me that provided the car is post-77 (when some brake-related ADR came into effect), and provided the engine fits within the 2.5x/3x rule, a brake upgrade is not required for engineering in Qld!
I'm still doing a brake upgrade of course, and it would be a top priority if I was turbocharging an old Celica. Wait a minute, I am turbocharging an old Celica.  Luckily I already have a brake upgrade (MA61 fronts) since the stockers were barely adequate for a stock 18R-G.
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Location:
Madrid - Spain
Registered:
August 2002
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Re: Rear discs vs. better fronts
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Tue, 05 October 2004 11:41
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While it is important that Engineers advise whats best for safety, they do have to work within certain guidelines. He probably has a good reason for making the request he has and it may be to satisfy a legal requirement in your state. Ask him to explain the regulations to you if you doubt him.
If all he wants is rear discs, the setup from a RT141 corona will pretty much bolt on. do a search and all the tricks will be revealed. I would definitly look into a front upgrade to go with it though. The standard ones have been the undoing of many a nice celica. And if your paying for an engineers certificate for a brake upgrade it may as well be a good one.
Oh and just with the engineering, what made you think that we would know better than a paid professional??? If you doubt him ask for his reasons. In the end, it doesn't matter what we think cos we can't give you a certificate to say it's legal.
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: Rear discs vs. better fronts
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Tue, 05 October 2004 11:54
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| mrshin wrote on Fri, 01 October 2004 18:51 |
There are still some people out there that believe the old idea that '4 wheel discs' = good brakes. Oh dear..
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as far as i'm concerned, 4 wheel discs = better than 1 warped drum
a warped drum will probably lock easier than a warped disc..
there is also the other problem of the leading shoes in the drums enhancing the braking effect, such that the braking force is not proportional to the applied force.
whilst drums may be more efficient for braking in terms of input force, a disc will be far more linear in it's braking effect..
sure the fronts may do around 70-80% of braking, but if your rears lock first, you are rooted
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Location:
Land of Oz
Registered:
June 2004
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Re: Rear discs vs. better fronts
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Tue, 05 October 2004 12:44
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Hi,
Drums are better at braking due to the more contact area the shoes have with the drum. Problem is the drum is not good at disapating the heat and with hard and continual application they get too hot and warp the drum, boil the fluid. Not good.
So, for normal driving, rear drums are fine. But, I agree with the others, the front brake upgrade would be better. Also get rear discs if you're gonna be doing a lot of hard braking. Also, if the engineer wants it, and he won't pass it without it, then I suppose you just gotta get rear discs.
seeyuzz
river
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